Cold Case: Looking For Life On Mars

Mar. 23, 2006 — Evidence never dies in the
popular TV show Cold Case. Nor do some traces of life disappear on
Earth, Mars, or elsewhere. An international team of scientists,*
including researchers from the Carnegie Institution's Geophysical
Laboratory, has developed techniques to detect miniscule amounts of
biological remains, dubbed biosignatures, in the frozen Mars-like
terrain of Svalbard, a island north of Norway. This technology will be
used on future life-search missions to the Red Planet.

"It might seem like we're looking for a needle in a haystack,"
remarked Carnegie researcher Marilyn Fogel.1 "But it's much better than
that. One of our studies showed that we can detect even the most minute
amounts of the element nitrogen, which can be evidence of life.
Interestingly, rocks might be particularly promising places to find
traces left by the tiniest microbes. Svalbard is brittle cold, very
dry, and rocky, much like the Martian environment, making it an
excellent test bed."

Nitrogen is essential to DNA, RNA, and protein. All life depends on
it. The scientists looked at how a certain type, or isotope, of
nitrogen was distributed in soils, water, rocks, plants, and in
microbes. They found that nitrogen quantities varied depending on how
the element interacted with the environment and living organisms. "We
found that organisms leave tell-tale nitrogen fingerprints on rocks, "
stated Fogel. "The technology is well suited for finding remains of
life on the rocky terrain of Mars."

In another study, the group found that they could adapt techniques
used in genetic laboratories to the field.2 They found that DNA
sampling and the polymerase chain reaction (PCR) method--which makes
many copies of a specific segment of DNA for analysis--can detect
genetic differences in rock-dwelling communities of blue-green algae
(cyanobacteria) and fungi. Further, they identified over 90 different
compounds that can be correlated to biosignatures of those life forms.
These fingerprints will be part of an enormous library of signatures to
which Martian samples can be compared in the search for life.

The work is presented in several talks at NASA's Astrobiology
Science Conference (AbSciCon) 2006 at the Ronald Reagan Building in
Washington, D.C., March 26-30.